Radio Frequency Identification (“RFID”) tags and systems have been widely adopted in recent years for the traceability and tracking of a wide variety of products and objects. Although these wireless systems are similar to UPC bar code type systems in that they allow for the non-contact reading of various products, items and devices, they are an effective improvement over UPC bar code systems in a variety of ways. In fact, RFID tags and systems can be vastly superior to bar code systems in many manufacturing and other hostile environments where bar code labels are inconvenient or wholly impractical. A significant advantage of RFID tags and systems is the non-line-of-sight nature of the technology, whereby tags can be read through a variety of substances such as snow, fog, clothing, paint, packaging materials or other visually challenging conditions where UPC bar codes or other optically read technologies would be useless.
Another advantage is that RFID tags can also be read at relatively high speeds, frequently in less than 100 milliseconds per tag, which can result in the ability of an RFID system to read hundreds of tags per second when combined with the non-line-of-sight nature of the technology. The read/write capability of an active RFID system can also be a significant advantage in applications where changes in the data for individual items is desired, such as work-in-process or maintenance tracking. In addition, most RFID tags comprise a user-programmable code that is typically 32 to 128 bits, whereby RFID tags can record much more information than a standard bar code, including items such as, for example, a unique identification code, where a device was manufactured, where it was sold, and who purchased the device.
RFID tags come in a wide variety of shapes and sizes, and are usually noted for their particularly small and unobtrusive nature. Large RFID tags include, for example, the hard plastic anti-theft devices attached to merchandise in stores, credit-card shaped tags for use in access applications, and screw shaped tags for use with trees or wooden items. In smaller versions, animal tracking tags inserted beneath the skin can be as small as a pencil lead in diameter and one-half inch in length. Tiny RFID tags can be even of a size on the order of a flat square measuring about 500 microns per side (i.e., the size of a flake of pepper), although tags this small typically require an antenna of at least a half an inch to four inches or more, depending on the application. Applications and venues utilizing some form of RFID tags and systems vary dramatically and can include, for example, package delivery, luggage handling, highway toll monitoring, livestock identification, and automated vehicle identification systems, among others. In addition, RFID tags can be implemented in a wide variety of general product inventory and tracking applications that range from washable RFID tags designed to be sewn into clothing to specially designed RFID tags and antennae for automobile tires. Even the European central bank is considering embedding tiny RFID tags into banknotes by 2005.
In most applications, an ordinary RFID system comprises essentially three primary components: 1) one or more transceivers for transmitting and receiving radio frequency signals, 2) at least one transponder electronically programmed with data, preferably comprising unique information, and 3) at least one antenna. The transceiver is generally analogous to a bar code scanner, and controls communication within the system by restricting when and where data is written, stored and acquired. The transponder is generally analogous to a bar code label, and typically comprises at least a small chip containing an integrated circuit, with this chip often being referred to as an RFID Integrated Circuit (“RFIDIC”). Antennae are essentially the conduits between RFIDICs and transceivers, as RFIDICs are frequently too small to act as their own antennae and collect a sufficient level of emitted radio signals standing alone. Antennae can be attached to the transceiver, the transponder, or both, and are generally used to emit and/or collect radio signals to activate an RFIDIC, read data from the RFIDIC and/or write data to it.
In general, the term “RFID tag” refers to the combination of the RFIDIC and the antennae attached thereto. An RFID tag is essentially a miniscule microchip, with attached antennae, that listens for a radio query and responds by transmitting an identification code that is frequently unique to that RFID tag. In operation, the transceiver generally emits radio waves in ranges of anywhere from a fraction of an inch to 100 feet or more, depending upon the power output and radio frequency utilized. When an individual RFID tag passes through an electromagnetic zone covered by the transceiver, it detects the activation signal of the transceiver and responds by emitting its individual recorded code. The “reader” or transceiver then collects this emitted code and passes this data along to a host computer or other like device for processing.
RFID tags are typically categorized as either active or passive. Active RFID tags are usually powered by an internal battery, can potentially even include a mini-processor, and can advantageously have read/write capabilities. Such active tags, however, tend to be relatively large and costly and tend to have a limited operational life. Conversely, passive RFID tags operate without a separate external power source, as power sufficient to operate a passive RFID tag is actually generated from the radio waves emitted by the transceiver. Although such passive tags generally cannot comprise a mini-processor or have read-write capabilities, they tend to be smaller, lighter and less expensive than active tags, and have a potentially infinite operational life. Such passive or “read-only” type tags are typically “write-once” type of integrated circuits, programmed with a unique set of data that cannot be modified, and essentially operate as a static data entry into a database, similar to the way that UPC bar codes are used. Due in part to the relative simplicity and lower costs, the majority of actual RFID tags fall into the “passive” category.
A wide variety of antenna materials and types are possible for RFID tags, and such antenna materials can include thin strips or traces of metal or other conducting material fabricated onto a specifically designed substrate or other medium. Such a medium can be specially provided, or actually built into the product containing the RFID tag. In one example, the military is working with RFID designs where the antennae are conducting threads built into the clothing of personnel to be tracked in the field. Standard apparatuses and methods for manufacturing RFID tags are well known, and instances of such apparatuses and methods can be found, for example, in U.S. Pat. Nos. 6,100,804 and 6,509,217, both of which are incorporated herein by reference in their entirety.
A major barrier to the broad adoption of tiny RFID tags and similarly advanced technologies in the thin-margin businesses of retail sales and consumer commodities has been the high cost of the equipment. For the tags alone, many manufacturers can expect to pay a relatively premium price per tag in low quantities. In quantities of about 1 billion, however, costs for RFID tags can drop significantly, and in lots of 10 billion or more, further reduced costs permitting for widespread adoption of the tags are hoped to be possible. In order for such low costs to be realized, however, it is generally accepted within the industry that significant improvements to and streamlining of the manufacturing process of such tags will be needed. One area where improvements may be possible is in the design and attachment of antennae to the RFID tag.
A typical passive RFID tag comprises a two pole RFIDIC connected to an antenna that is fabricated onto a substrate. Alternatively, a passive RFID tag can comprise a four pole RFIDIC with at least one and usually two of the poles connected to an antenna. Additional poles can either be “dummy” poles that do nothing, or can be used in conjunction with a battery or external power source, in the case of active or otherwise powered RFID tags. A wide variety of apparatuses and techniques exist for providing poles on RFIDICs to which antennae can be attached, with one example being gold bumps formed on an “active” side of the chip, such methods as will be readily known and understood by those skilled in the art. Advantages of techniques such as the formation of gold bumps to attach antennae include higher throughput, lower assembly costs, and the ease of accommodation with respect to differing sizes and shapes of RFIDICs and antennae.
Disadvantages of such techniques, however, tend to include the necessitated use of individual pick and place methods for orienting each RFIDIC during manufacture, such as before attaching each antenna to each RFIDIC. That is, the manufacture of RFID tags typically requires that any particular RFIDIC be oriented in a particular position before the antenna or antennae can be attached to the tag in an operable manner. Such specific orientation requirements result in the need for individualized handling of each RFIDIC to some degree, such that standard pick and place robotics or similar apparatuses or techniques are popularly used during the manufacturing process. The use of individual pick and place manufacturing devices and techniques, however, tends to result in a significantly slower and costlier manufacturing process, and precludes the use of many more favorable alternative bulk manufacturing methods and techniques.
Accordingly, there exists a need for improved apparatuses and methods for attaching antennae to RFIDICs that permits the use of more favorable bulk manufacturing methods and techniques, and specifically a need for improved RFIDIC designs and manufacturing techniques such that individualized pick and place devices and methods are minimized or eliminated.